One of the challenging aspects in sawmilling is the handling of the uncut logs; as the logs can be heavy and awkward. Proper sawmill operations require that the sawlog be firmly clamped into position so that it cannot move during milling. Log clamping generally requires two elements—one or more vertical log rests against which the log rests, and one or more log dogs which firmly hold and lock the log against the log rest(s). Typically locking the sawlog against the log rest(s) requires two simultaneous steps from the operator—the operator must roll the log and hold it against log rest(s) with a cant hook or other leveraging tool while, at the same time, operating the log dog(s) so as to set it and lock it in place. It can be difficult to leverage the log and then operate the log dog(s) separately because the log usually rolls backwards and therefore prevents the log dog(s) from properly binding the sawlog against the log rest(s). Thus, the operator has to perform both actions simultaneously. This requires coordination and considerable strength given that the operator leverages the sawlog (which can weigh hundreds of pounds) with one hand while the other hand operates the horizontal and vertical positioning of the log dog(s).
A number of portable sawmills having means, such as a log dog to hold a log in place, have been described in the art.
U.S. Pat. No. 5,784,941 describes a portable sawmill in which the functions of adjusting a cut and making a cut are divided between two separate devices. The invention discloses a vertical chain saw, ideally operated in an upward direction. The patent also discloses a log restraint system comprising a setwork having a headstock and a lockable L-shaped log dog, joined by a clamp which is locked with a lever.
U.S. Pat. No. 4,640,170 discloses a portable saw mill with a frame that surrounds the log. The frame is dragged or slid along a frame supporting surface. The frame holds a chain saw at the two ends of its blade, in horizontal fashion, with chain saw support members. The invention uses sliding means for facilitating the movement of the frame over the log. The log is secured against rolling using a simple jig or similar means.
U.S. Pat. No. 4,275,632 describes a portable sawmill comprising a U-shaped support or carriage, holding a band saw. When in use, a log is placed between the two guide rails and is supported in place by appropriately distanced log supports.
U.S. Pat. No. 4,307,641 describes a portable sawmill comprising two skid rails, vertical support members, a pair of guide rails. The log is held in place by two externally threaded log screw pins with pointed ends.
U.S. Pat. No. 4,300,428 describes a portable sawmill having a frame, a guide member mounted above the frame, and a carriage. The chain saw is mounted above the log, and operates at about a 45 degree angle to the horizontal. The log is held in place with log dogs which are adapted for hooking the log and holding it in position.
U.S. Pat. No. 4,235,140 describes a saw mill. The logs are held in place with a standard log dog attached to the cross members on which the log is placed.
U.S. Pat. No. 3,926,086 describes a portable saw mill that uses a complex pulley system to move the chain saw and supporting platform. When in use, a log is placed, and clamped, between the guide rails, using a set of circular discs eccentrically oriented on a rod.
U.S. Pat. No. 3,695,316 describes a portable timber milling jig that uses a carriage, holding a chain saw, axially surrounding a square guide rail. The chain saw is held at an approximately 45 degree angle and only uses one guide rail, and utilizes ball bearings on the carriage to move the carriage with respect to the guide rail. When in use, a log is placed under the guide rail, and fixed using clamping points driven into the center of the log, to which support clamps are fastened.
Canadian Patent No. 1,200,180 describes a portable saw mill comprising a frame with a guide rail and a carriage moveable along the guide rail. A band saw is supported by the carriage. The carriage is moveable along the guide rail along two sets of wheels, one engaged with the upper side of the guide rail and the other with the lower side. The log is held in place by its own weight, or by stops and a traditional locking dog.
U.S. Pat. No. 4,245,535 describes a portable sawmill with an elaborate hydraulic apparatus for cutting a log. The chain saw cuts in a vertical motion. The log is held in place using a log holding assembly having a toothed prod which grips the outer end of the log, and a cylinder which impales the inner end of the log with a ram, forcing the outer end against the prod.
U.S. Pat. No. 4,210,049 describes an “x” frame for holding a log, with a chain saw affixed to the frame in cantilever position for cutting logs crosswise. The log is held in the nook of the “x” frame.
Canadian patent application 2,541,734 to the present inventor describes a portable sawmill that is easily assembled and disassembled into portable components, and which can use generic components as its saw and/or guide rails. The log is held in place using traditional log dogs.
There is a need in the art for a log dog that permits the operator to set the log dog against the sawlog, and separately leverage the log against the log rest(s). In addition, there is a need in the art for a log dog where the height of the log dog can be adjusted. Further, there is a need in the art for a log dog that can pivot and be locked in place by a ratcheting mechanism to prevent movement of the log dog. Moreover, there is a need in the art for a log dog that can be attached to a framework that permits sliding of the log dog towards and away from the log. In addition to the above, there is a need in the art for a log dog assembly, a log support and clamp assembly having such a log dog that can assist with the handling, rolling and clamping of logs. In addition, there is a need in the art for a sawmill having such a log dog. Moreover, there is a need in the art for a kit for retrofitting a log dog to a portable sawmill that can help with log handling, rolling and clamping.